Cannot create new primary partition - only 2 primary partitions on disk

Discussion in 'Windows Vista Performance' started by Vistanoob, May 24, 2009.

  1. Vistanoob

    Vistanoob Guest


    I just tried to create a new primary partition using Disk Management.

    I get the error "You cannot create a new volume in this unallocated space
    because the disk already contains the maximum number of partitions."

    Ultimate goal is to create two more bootable partitions on my hard disk, one
    for Windows 7 and the other for Ubuntu. My C drive contains Windows Vista,
    my D drive has program files, and my E drive contains data.

    According to what I found online, you can have up to four primary partitions
    on a disk.

    According to DiskPart, this is what I have in terms of partitions:

    Partition ### Type Size Offset
    ------------- ---------------- ------- -------
    Partition 1 OEM 10 GB 32 KB
    Partition 2 Primary 38 GB 10 GB - C drive
    Partition 0 Extended 10 GB 48 GB - D drive
    Partition 4 Logical 10 GB 48 GB
    Partition 3 Primary 61 GB 58 GB - E drive

    Any suggestions will be welcome

    Vistanoob, May 24, 2009
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  2. Vistanoob

    Rick Rogers Guest


    According to disk manager, you already have the max allowed. Only through
    the use of a third party utility like BootIT NG would you be able to get
    around this limitation.

    Leave the unallocated space as it is and allow setup for the other OS's to
    create the necessary installation volumes from the free space. In the case
    of Ubuntu, this will be necessary as Windows would not be able to create the
    necessary ext volumes.
    Rick Rogers, May 24, 2009
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  3. Vistanoob

    GrahamH Guest

    As stated you already have the max amount of partitions for your drive.
    Four primary partitions are only possible if you dont have an extended
    Could you not buy a second hard disk and then use that for your programs and
    This will enable your Data to be accessible from all your operating systems
    as well as being safer.
    GrahamH, May 24, 2009
  4. The extended partition IS a primary partition and counts as being one of the
    4 primary partitions allowed.
    Richard Urban, May 24, 2009
  5. Vistanoob

    R. C. White Guest

    Hi, Vistanoob.

    Have you ever seen a Partition Table on a hard disk drive? Most users never
    have. It really is quite simple. Just 64 bytes on the first physical
    sector of a physical hard drive. It's not a file or part of a file because,
    at the point during startup when the not-yet-fully-awake system needs this
    information, it doesn't yet know how to deal with files or folders. The
    first physical sector on the disk holds just 512 bytes of code (same as
    every other sector on the disk). About 400 bytes of this represents the
    mysterious(?) MBR (Master Boot Record) that we've all heard about. And,
    starting at offset 01BE of that first sector, we find the Partition Table,
    which looks like this (copied from

    80 01 ..
    000001C0: 01 00 07 FE BF 09 3F 00 - 00 00 4B F5 7F 00 00 00 .?...K.....
    000001D0: 81 0A 07 FE FF FF 8A F5 - 7F 00 3D 26 9C 00 00 00
    000001E0: C1 FF 05 FE FF FF C7 1B - 1C 01 D6 96 92 00 00 00
    000001F0: 00 00 00 00 00 00 00 00 - 00 00 00 00 00 00

    It would be more obvious that those are 4 rows of 16 bytes each if it didn't
    start near the end of each line (like a calendar for a month that starts on
    Friday). That first 16-byte entry is really:
    80 01 01 00 07 FE BF 09 3F 00 - 00 00 4B F5 7F 00

    The "80" says that this is an Active (bootable) partition. The next byte
    says this partition starts at Head 1. The next 2 bytes tell the starting
    sector and cylinder (using 6 bits and 10 bits, rather than 8 bits each).
    The next byte (07) says this partition uses an Installable file system:
    NTFS, most likely. If this byte is 05 (rather than 07), this partition is
    an "Extended Partition". The next bytes tell the starting and ending
    sectors and the size of the partition.

    That's all. The partition table doesn't have room to store any more info
    about the partition, and it doesn't have room for more than 4 entries.

    So, how do we get more than 4 partitions on one disk? We don't (unless we
    use a 3rd-party system, such as BootItNG). But if the 5th byte for one of
    the partitions is 0E, then there is an EBR (Extended boot record) somewhere
    else on the disk that can hold similar entries for one or more Logical
    Drives. (I've not been able to find and actually SEE and EBR on my hard
    drives, so you're on your own for exploring this subject further.)

    In your case, DiskPart says that you have 4 partitions already: Partition 1
    (OEM), Partition 2 (Drive C:), Partition 3 (Extended) and Partition 4 (Drive
    E:). I suspect that you've misread the DiskPart entry for your Drive D:.

    Your Extended partition is NOT Drive D:. A drive letter is never assigned
    to an extended partition. Your Drive D: is the first (only) Logical drive
    IN the Extended Partition. Note that the Logical drive starts at offset 48
    GB (from the beginning of the HDD), same as the beginning of the Extended
    Partition. You could easily create additional Drives F:, G:, X: and others
    within the Extended Partition (if your Drive D: were not already using all
    of the Extended Partition's 10 GB of space). None of those would require an
    entry in the disk's Partition Table; they would all be entries within the

    If you really want to understand these concepts, Vistanoob, find a copy of
    the Resource Kit for Windows Vista (or any other Windows version) and invest
    an afternoon in studying at least the "Troubleshooting Disks and File
    Systems" part. If you can't find the book (which has well over 1,000 pages
    and costs $50 or more), then read it online at the link I gave above.
    Several hours invested here will pay dividends, not just for this problem
    but for as long as you use computers - which may be the rest of your life.
    I'm grateful for the many hours I spent back in the 1980's with Norton
    Utilities, especially DiskEdit, which let me read my disks, byte by byte,
    and explained what those bytes meant.

    But I know nothing of Ubuntu or Linux or other operating systems.

    R. C. White, CPA
    San Marcos, TX

    Microsoft Windows MVP
    Windows Live Mail 2009 (14.0.8064.0206) in Win7 Ultimate x64 RC 7100
    R. C. White, May 26, 2009
  6. Vistanoob

    Vistanoob Guest

    Lots of good information here - thank you RC and all who replied.

    I may wind up

    1. deleting partition E after a backup - it's just data, no program files
    2. increasing the size of the extended partition on which drive D lives, and
    creating a new logical drive E there for my data
    3. creating a new primary partition in the remaining unallocated space on
    which Windows 7 or Ubuntu could live.

    That would keep me to a total of four partitions.

    Any advice on step 2 - increasing the size of the extended partition on
    which drive D lives but keeping drive D to its present size?

    Vistanoob, May 28, 2009
  7. Vistanoob

    R. C. White Guest

    Hi, Vistanoob.

    Your step 2 sounds like a good plan to me. ;<)

    One little gotcha that you probably already know about: When you Extend the
    partition, specify the space in MEGAbytes, not Gigabytes. The first TWO
    times that I Extended a volume, I put in "10" for a 10 GB extension - and
    the volume grew by the full 61 GB (in your case)! It seems that 10 MB was
    too small, so Extend used the default - which is ALL the available space.
    So put in 10,000 MB, not 10 GB.

    R. C. White, CPA
    San Marcos, TX

    Microsoft Windows MVP
    Windows Live Mail 2009 (14.0.8064.0206) in Win7 Ultimate x64 RC 7100
    R. C. White, May 28, 2009
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